Abstract
Synthesis of structurally modified poly(vinyl alcohol) (PVA) ionic composites is presented. Low-molecular-weight PVA (Mn = 18,000 g mol-1) is prepared and blended together with either copper or borate ions under ambient conditions to yield PVACu and PVAB ionic composites, respectively. The borate ions coalesce together with different polymeric chains of PVA, forming a 3D network structure, which is identified by the weakening of ?OH absorption in the infrared spectrum. On the other hand, copper ions yield a weakly crosslinked polyelectrolyte by forming a coordinated complex with the hydroxyl groups of PVA, which leads to an increase in the ?max value in the ultravioletvisible spectrum. The surface morphology of these PVA-based ionic composites is studied via atomic force microscopy. Furthermore, the quantitative estimation of copper in PVACu composites is performed by atomic absorption spectroscopy. Among these PVA ionic composites, the PVACu exhibits excellent moisture absorption capability and dramatic changes in the color of thin composite film, when exposed to 75% humidity atmosphere. The absolute recovery, recyclability, and stability of the PVACu ionic composites not only enable them to be good humidity indicators but the results show that these composites can be employed as efficient humidity-sensitive material on suitable transducers for environmental and industrial applications. POLYM. COMPOS., 2012. (C) 2012 Society of Plastics Engineers